I've been recently experiencing troubles after login Ubuntu 12.04. After typing the password the whole screen turns black for like 20 secs. Oddly enough, after that it turns sort of gray and the mouse shows up so you can move it. As I have some docs on the Desktop, I've noticed that passing the cursor over them 'reveals' the icons while the rest of the screen stays gray/black.
If one tries opening a window, both by clicking on one of this icon or just with
alt + ctrl + T, the screen goes back to normal except top bar is not there, moving the cursor to the top left corner won't do anything and typing inside the window doesn't work (however the search little box shows up).
Moreover, after all that events described before error message such as Ubuntu 12.04 has experienced an internal error and system program problem detected.
Any guesses about the nature of this problem? How may I solve it? I'd rather not be back to using Unity, I don't like it very much.
Thanks to everybody!